German police investigating the disappearance of Madeleine McCann have discovered a sealed-off cellar after excavating an allotment site just outside Hannover.
Witnesses said on Wednesday they had watched as the BKA, the German federal investigators, lifted off a cement block covering the basement during the first day of digging at the council-owned site.
After discovering the underground cellar, officers led in a sniffer dog, which barked when it entered, the Telegraph can reveal. "The sniffer dogs were barking quite a lot in the morning," said one person present.
Authorities began searching the site on Tuesday, in connection with the disappearance of three-year-old Madeleine. German police believe that she is dead.
Last month, Christian Brückner, 43, was named as the prime suspect in what German authorities' are treating as a murder investigation. Brückner, a convicted paedophile, was living in the Algarve in Portugal when Madeleine went missing in May 2007.
German police claim they have evidence linking him to the case. While he was living in Hannover, he was convicted of two crimes.
By Tuesday evening, police in Hannover had dug a 2m-deep hole in the ground at the centre of the allotment, with forensic tents erected next to it. The dig continued on Wednesday from 7am in a different area of the garden.
Cement and other heavy duty materials were seen being removed from the site in the town of Seelze, just outside Hannover. At least seven police vehicles including a truck were present at the cornered off plot.
Wolfgang Kossack, 73, who owns the plot next to Brückner's former allotment, told the Telegraph that a man with two dogs lived in the run-down shed on the site in 2007, the same year Madeleine McCann disappeared.
He said: "I can't tell you if it was the same guy. What I can tell you is that he was there with two dogs. One was small and brown the other one was large and black. He was there for between eight and nine months around about 2007. I went on holiday one July and when I came back he was gone."
He and his wife had a few "uncomfortable situations" with the man. His dogs defecated in their garden, and the man's car, a cream-coloured VW camper van, "stank of diesel". Kossack recalled: "At first, he apologised but he became increasingly aggressive."
That description fits that of the 43-year-old Brückner, who had two dogs while living in Hannover. While still in Portugal, he drove a white and yellow VW Westfalia camper van.
Residents living next to the five allotment plots said they were "disused and overgrown" and had been for years. The shed was falling apart.
Kossack said: "It was more of a ruin than a house. He tried to do up the roof and insulate it and he seemed to sleep there from time to time. When he left he took down everything that he had built as he had to leave it as he found it."
Another man, who lives across the road from the plot, said: "The people there were just normal folks who didn't live there. They just came here to get away from the city."
"I can't remember anything about the people who were there, but there was a Volkswagen camper that would turn up now and again. It was white and red."
• Madeleine McCann case: German garden searched for clues in missing girl case
• Madeleine McCann's parents' heartache as German cops prepare to drop investigation
• Madeleine McCann: 'Glimmer of hope' for parents as Portuguese police launch new search
• Madeleine McCann 'murder' suspect told barmaid 'the child is dead and that's a good thing'
Brückner was found guilty of two crimes during his time in Hannover. In 2010 he was charged with falsifying documents and ordered to pay a fine. Three years later, he was convicted of theft. He did not serve a prison sentence.
Shortly after, he left the city and went to nearby Braunschweig (Brunswick), where prosecutors are running the investigation against him.
While in Hannover he lived in a high-rise apartment block in Linden, a neighbourhood known for its lively nightlife. One neighbour said a man and woman who fitted the description of Brückner and his girlfriend had lived in a bottom floor flat on Liepmannstraße.
While admitting that she did not know them personally, she said "there was something strange about them, they didn't fit in."
Locals said that he was a regular at Club Havana, a bar where he was known as "the workman" due to the fact he often smelt of diesel and was known to spend his free time repairing engines.
He also stood out in the local nightlife due to the fact that he would bring his two dogs – a dachshund named Frau Muller and a rottweiler named Charlie – with him wherever he went.
Madeleine McCann's disappearance: A timeline of the events
May 3, 2007
Kate and Gerry McCann leave their three children — Madeline, Amelie and Sean — asleep in their holiday apartment in Praia da Luz, Portugal, while having an evening meal with friends. Later that night, three-year-old year Madeleine goes missing from her bed. The following day, an investigation is launched into her disappearance by Portuguese police.
May 14, 2007
Robert Murat, an Anglo-Portuguese man, is questioned by the Portuguese police and named an official suspect, or arguido.
August 3, 2007
100 days after Madeleine's disappearance, investigating officers publicly acknowledge that the three-year-old year could be dead.
September 7, 2007
Gerry and Kate McCann are questioned by Portuguese police and are named as official suspects — or arguidos — within the case.
October 2, 2007
Goncalo Amaral, the Portuguese detective in charge of the inquiry, is removed from the case after criticising the British police in a Portuguese newspaper interview. He is later replaced on October 9 by Paulo Rebelo, a senior Portuguese detective.
March 19, 2008
Kate and Gerry McCann are awarded £550,000 libel damages and front-page apologies from the Express Newspapers over allegations they were responsible for their daughter's death. The apology headline reads — "Kate and Gerry McCann: Sorry".
July 21, 2008
The Portuguese authorities end their investigation and remove the arguido status of Gerry and Kate McCann as well as Robert Murat.
Under the guidance of Home Secretary, Theresa May, Scotland Yard launches Operation Grange. The operation led by the Metropolitan Police Service aims to review the circumstances of Madeline's death.
April 25, 2017
Met Police Assistant Commissioner Mark Rowley says that the police have "a significant line of inquiry" that is "worth pursuing", but stresses that there is no "definitive evidence" as to whether Madeleine is dead or alive.
June 5, 2019
The government announces in June 2019, that it will continue to fund Operation Grange until March 31, 2020. The Home Office also confirm that £11.75 million has been spent on the operation since 2011.
June 3, 2020
Scotland Yard identify a German man as the main suspect in the disappearance of Madeleine McCann.